Slashdot Mirror
Nanotechnology + Superconductivity = Spintronics
karvind writes "Spintronics is a nanoscale technology in which information is carried not by the electron's charge, as it is in conventional microchips, but by the electron's intrinsic spin and if a reliable way can be found to control and manipulate the spins spintronic devices could offer higher data processing speeds, lower electric consumption, and many other advantages over conventional chips--including, perhaps, the ability to carry out radically new quantum computations. PhysOrg is reporting that University of Notre Dame physicist Boldizsar Janko and his colleagues have found a way to achieve this control using a magnetic semiconductor, insulator and superconducting material stack of thicknesses of order of few dozen nanometers. IBM and Stanford are also looking into spintronics."
Seems like one of the Unsolved Problems in Physics isn't exactly unsolved anymore.
Are you SURE this isn't a technology developed jointly by the press and the White House?
R(k)
Microsoft is reportedly already somewhat advanced in spintronics. A company offical reportedly said "We consider ourselves to be industry leaders when it comes to manipulation using spin."
What's the cheapest device that I, a layman, can buy to set the spin of large amounts of electrons (several coulombs per second) to a certain value?
--
make install -not war
I know this isn't exactly what the article said, but I had a thought. If computers could base data on spin and charge at the same time (4 possibilities), would there be any significant advantage to being able to work natively in base 4 instead of base 2?
"We are the Dyslexia of Borg. Your ass will be laminated. Futility is resistant."
How does Spintronics stack up against Plasmonics? I mean, they're both being touted as The Next Big Thing in chips. Are the compatible in any way? Different time frames?
Spintronics also represents one of the quickest transitions from lab to market, next to the transistor via GMR sensors. The hard disk read heads on the hard drives in your computer, if you bought a new disk in the past few years, already incorporates spintronic effects through GMR (Giant MagnetoResistance). Most major media storage and also electronics companies have been heavily investigating spintronics for years too, not to mention a good percentage of condensed-matter physicsists, electrical and materials-science engineers.
Spintronics is also being investigated for quantum computation because the two electron eigenstates in any direction (up / down) can make a good basis for the Zero and One states of a qubit.
But to repeat the hype, spintronics does have potential to revolutionize the electronics industry by offering a whole new degree of freedom to manipulate of the electrons. 'Classical' transistors move/detect/switch charge, adding spin to the picture allows much more flexibility, and probably higher device speeds or data densities. Eg, perhaps microprocessors can go from binary as presence/lack of charge to spintronic up/down charge. Or perhaps even base-4 using presence/absence of both spin up and spin down flavors of electrons.
Memory now doesn't use positive and negative charge, it already uses magnetic fields. So it will still be binary, spin up and spin down.
Particles with integer spin, such as phonons (spin 0), photons (spin 1), gravitons (spin 2) are called Bosons and obey Bose-Einstein statistics. Any number of bosons can be found in any quantum state, and at low temperatures they can condense into the ground state via Bose-Einstein Condensation.
Particles with half-integer spin, such as electrons, protons, neutrons (all spin 1/2) are called Fermions, and obey Fermi-Dirac statistics. This means interchanging two fermions in a system will cause the wavefunction of the system to acquire a factor of negative one. So if two fermions are in the same quantum state, that component of the wavefunction must be equal to it's negative - meaning zero. This is the Pauli Exclusion Principle, meaning no two fermions can ever exist in the same quantum state of a system. This effect has profound impact on physics, accounting for orbital nature of atoms, band structure of semiconductors, etc.
Anyway, back to your question about spin, another aspect of spin is that the allowable spin values must differ by integer units of hbar. So electrons, with total spin of hbar/2 are allowed two states that differ by hbar - +hbar/2 and -hbar/2. Usually the direction is chosen by an applied field, or whatever direction is chosen to measure the electron spin.
Spin is tricky because it isn't simply additive, but follows appropriate group theory. Electrons are part of SU(2) algebra, and spin interactions are weird. For example, you can simultaneously know the total spin (electrons are always hbar/2) and the spin component along one direction (for electrons this could be +hbar/2 and -hbar/2). But you cannot know the x, y, and z components simultaneously, basically because the Pauli matrices don't commute (Heisenberg uncertainty principle). So in actuality a spin-up electron really points somewhere along a cone that mostly points up, but you don't know more than that.
With two electrons, you can simultaneously know EITHER the total spin of the pair AND the total spin projected along one axis, OR you can know the projections of the two independent spins along one axis. If one electron is up and another is down, the system is in a state of 1/sqrt(2) (spin-Zero + spin-One). Also - this means that the two-electron system can exist in a Spin-1 state with the spin in one direction zero, or a Spin-0 also with the spin in one direction zero. Since the two electrons would have an integral number of spin, the system acts like a Boson. This is what allows superconductors, which are mentioned in TFA, to pair up and effectively condense.
Additionally, the spin-zero state of two electronss is very important in quantum communication, quantum teleportation, and quantum computation. This is the state with total spin zero, so no matter what direction you measure one spin, the other spin is aligned opposite.
I carry the cables for his spintronics! Ya gotta believe me!
Hmmm... I seem to remember this...but I can't find record of it on slashdot. can anyone remember if this has come up somewhere before?
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-shpoffo
Is it too late to stop the proliferation of "-tron" words? "-tron" means nothing; "electrons" are so called because of the Greek word for amber, which the Greeks knew to be capable of producing a static charge. What if people abstracted part of that word out and started calling every new technology "something-ber"?
I think the technical name for the combining from "-tron" is a "cranberry morpheme," from "*cran," which apparently has no independent meaning.
Shop as usual. And avoid panic buying.
Additionally, the spin-zero state of two electronss is very important in quantum communication, quantum teleportation, and quantum computation. This is the state with total spin zero, so no matter what direction you measure one spin, the other spin is aligned opposite.
Oddly enough, free electrons do not have well-defined spin directions (interference phenomena destroy any possibility of measuring it, so it does not exist). Because of this it is not the case that electron-spin correlation is important to quantum communciation. Photon linear polarization alignment in J=0 states, which is the spin-1 analogue of the spin-zero state of two free electrons, is important, though. And bound electrons do have well-defined spin directions, which is what creates interesting effects in superconductors etc.
--Tom
Blasphemy is a human right. Blasphemophobia kills.
Science publications only really profit if done in respected peer-reviewed journals. In the research world, PhysOrg and the like don't mean much for getting funding.
Scientific American (warning: loaded with ads etc)
Not for the light-hearted, a thorough review in Reviews of Modern Physics (subscription required, if you cannot access the article, drop me an email at karvind@NOSPAM.gmail.com)
On Ferroelectric spintronics from Colossal Storage.
Spintronics and Quantum Dots. Discussion about one possible implementation.
Another good introduction.
Hope it helps.
In the next 50 years or so do you think that photonics or spintronics will become the main technology behind computation, or will we see a hybrid computer that uses the best of both technologies (e.g. computation/cpu using spintronics and data transport in buses between devices/peripherals using photonics)?
You retard RTFA:
Now, University of Notre Dame physicist Boldizsar Janko and his colleagues believe they have found such a control technique. Their work, funded by the National Science Foundation through a Nanoscale Interdisciplinary Research Team grant, was published in the March 5, 2005, edition of the journal Nature.
I work in a biochemistry lab and if you can get a publication in one of the two most highly ranked journals Science or Nature, it helps you greatly in getting funding (as they have from NSF) or tenure.
The spindizzy drive will give us Cities in FLight. I would like to recommend Seffner, Mango, or maybe Wimauma as Florida burgs to spin out.
Too lazy to create a sig...
...Nanotechnology + Superconductivity = Supertechnonanocondoexpialidocious
Mr. T pitied this fool on 27 July 1992.
Nice way to demonstrate your maturity. Makes me wonder if it's worth the time to bother replying to you.
Anyway, I did RTFA, and was responding to the parent's claim (or overextended southpark joke) that merely mentioning a bunch of trendy technobabble words in PhysOrg implies profit. That's why I specifically referred to "real" peer-reviewed journals.
it has already imagined a beowolf cluster of itself!
Have a look at some of the google ads that appear around the article : ) "Life-prolonging magnets" "Immortality device".... : )
No, no sig. Really.
ThePromenader
Why? The -tron (or more accurately the -on suffix) words aren't Greek. They serve a useful purpose and the suffix is used in a single fairly well-defined way. I find it to be an ingenious solution to the labeling of particle-like objects.
Spin Wave technology is nothing new, for that matter it's just it's nature,and then we "doscovery" it as something new. Check out: http://www.hightechscience.org/spin_wave_technolog y.htm
For those interested in Spintronics and Quantum Entanglement visit this website.
http://colossalstorage.net/